freebsd-performance Digest, Vol 4, Issue 9

Eric Anderson anderson at
Mon Jun 23 05:58:53 PDT 2003

Alexander Leidinger wrote:
> On Thu, 19 Jun 2003 07:37:25 -0500
> Eric Anderson <anderson at> wrote:
>>Interestingly enough, I found FreeBSD 4.8 to be faster at local disk 
>>writes than FreeBSD 5.1.  About 50% faster.
> 5.1 isn't tuned yet to deliver high performance, so it isn't a surprise
> to see a lower performance than 4.x. But 50% is much... are you sure you
> did the test under the same conditions (e.g. are you sure the write
> cache was off (or on) in both cases, no debugging switches activated in
> the kernel/userland)?

I attempted to create the same environment, but I didn't force anything 
to be the same.  In other words, what I did was swap the boot drive out 
from 4.8 to 5.1 and back again, each time testing the differences in 
speed.  Same RAIDed partitions were tested, so it was tested on ufs, 
with the same tests, and consistant results.  I didn't turn on/off write 
caching on either, so if the defaults are different between them, that 
could be the problem..


Eric Anderson	   Systems Administrator      Centaur Technology
Attitudes are contagious, is yours worth catching?

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